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The charge‐transfer states in a stacked nucleobase dimer complex: A benchmark study
Author(s) -
Aquino Adélia J. A.,
Nachtigallova Dana,
Hobza Pavel,
Truhlar Donald G.,
Hättig Christof,
Lischka Hans
Publication year - 2011
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21702
Subject(s) - nucleobase , polarizable continuum model , density functional theory , thymine , chemistry , computational chemistry , molecular physics , polarizability , charge (physics) , guanine , singlet state , chemical physics , excited state , physics , molecule , atomic physics , solvation , quantum mechanics , dna , nucleotide , biochemistry , organic chemistry , gene
Electronic singlet excitations of stacked adenine–thymine (AT) and guanine–cytosine (GC) complexes have been investigated with respect to local excitation and charge‐transfer (CT) characters. Potential energy curves for rigid displacement of the nucleobases have been computed to establish the distance dependence of the CT states. The second‐order algebraic diagrammatic construction [ADC(2)] method served as reference approach for comparison to a selected set of density functionals used within the time‐dependent density functional theory (TD‐DFT). Particular attention was dedicated to the performance of the recently developed family of M06 functionals. The calculations for the stacked complexes show that at the ADC(2) level, the lowest CT state is S 6 for the AT and as S 4 for the GC pair. At the reference geometry, the actual charge transferred is found to be 0.73 e for AT. In case of GC, this amount is much smaller (0.17 e ). With increasing separation of the two nucleobases, the CT state is strongly destabilized. The M06‐2X version provides a relatively good reproduction of the ADC(2) results. It avoids the serious overstabilization and overcrowding of the spectrum found with the B3LYP functional. On the other hand, M06‐HF destabilizes the CT state too strongly. TD‐DFT/M06‐2X calculations in solution (heptane, isoquinoline, and water) using the polarizable continuum model show a stabilization of the CT state and an increase in CT character with increasing polarity of the solvent. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011